Straddle-Type Vehicle

ABSTRACT

A straddle-type vehicle ( 100 ) includes a frame ( 20 ) and an engine ( 10 ) mounted on the frame ( 20 ). The engine ( 10 ) includes a cylinder head ( 11 ) positioned toward the rear end of the frame, and located below a saddle seat. The cylinder head faces toward the rear end of the frame, which allows the heated cylinder head of the engine and the exhaust pipe connected to the cylinder head to avoid the position where the user&#39;s legs contact the vehicle while riding, so the effect of heat emitted from the cylinder head on the rider&#39;s experience is reduced.

RELATED APPLICATION INFORMATION

The present application claims the benefits of priority to ChinesePatent Application No. 201911029709.3, filed with the Chinese PatentOffice on Oct. 28, 2019. The entire contents of the above-referencedapplications are incorporated herein by reference.

FIELD OF THE DISCLOSURE

The present application relates to a straddle-type vehicle.

BACKGROUND OF THE DISCLOSURE

The background discussion provided herein is intended to facilitateunderstanding of the technical content of the present application, andis not necessarily admitted prior art.

The English meaning of ATV is All-terrain vehicle, which is a means oftransportation suitable for all terrain, and is abbreviated to ATV; ATVsmay also be called “beach vehicles”, and are also known as “all-terrainfour-wheel off-road locomotives”. The vehicle is simple and practicalwith good off-road performance. ATVs are equipped with wide tires toincrease the area that the tires make contact with the ground,generating greater friction and reducing the pressure of the vehicle onthe ground, making it easy to drive on beaches, riverbeds, woodlandtrails, streams and harsh desert terrain.

It is difficult to express the meaning of an all-terrain vehicle in asimple Chinese name. According to its appearance, it can be translatedinto “all-terrain four-wheel off-road locomotive”, but such atranslation still feels confusing. On soft sand, the ATV's wide tirescan increase the area that the tires contact the ground, therebygenerating greater friction, and unique tread patterns make spinning andskidding of the tires more difficult, making the vehicle easy to driveon the sand. But in fact, a good, high-performance ATV can not only bedriven on beaches but also on riverbeds, woodland trails, streams andeven on harsher desert terrain. ATVs are great for transporting peopleor goods, making the ATV a full function all-purpose vehicle of action.

Depending on the displacement size and the external characteristics ofthe vehicle, ATVs are commonly divided into:

Utility type, with its shape being square and upright a bit like aWillys Jeep (It's called “ jeep type” in Taiwan), its most pronouncedfeature is to be provided with front and rear shelves or carriers;making the vehicle multi-functional and extremely practical. It can beused for carrying goods, farming, hunting, etc.

Sport type, with a streamlined appearance that is very sporty, which issuitable for high-speed driving, leaps, stunts, etc. ATV races aremainly based on sport type ATVs.

Military type, referring to a vehicle that can travel on any terrain.The most distinctive feature is that it can travel freely over terrainthat is difficult for ordinary vehicles to be maneuvered. Classified bytravelling mode, all-terrain vehicles have two types: wheeled andtracked. The military potential of ATVs has been recognized by more andmore military forces, and its development is ascendant. The militarytype family is huge, with but a variety of models and novel styles.

At present, all-terrain vehicles are more and more popular amongconsumers. One style is the straddle type vehicle, which is generallyequipped with a single-cylinder engine. The existing arrangement of theengine of the straddle type vehicle arranges the cylinder head of theengine near the front. This arrangement results in an exhaust pipe andtubular muffler running the whole length of the vehicle, which makes ithotter near the driver's body, especially near the legs, thus thedriver's riding comfort is reduced.

In summary, how to improve the driver's comfort while driving a straddlevehicle has become a technical problem for those skilled in the artwhich urgently needs to be solved.

SUMMARY OF THE INVENTION

The purpose of the present application is to disclose a straddle-typevehicle with improves the driving comfort and driving experience of thedriver.

In order to achieve the above purpose, the present application adoptsthe following technical solution: a straddle vehicle includes: a frame;a wheel assembly including front and rear wheels arranged under theframe; an engine mounted on the frame for providing power for thevehicle, the engine including a main body and a cylinder head connectedto the main body and positioned above the main body; an intake andexhaust system, including an intake assembly for supplying air to theengine and an exhaust assembly for discharging exhaust gas generated bythe engine; a brake system associated with the wheel assembly, includinga parking assembly and a brake assembly; a transmission system installedon the frame for transmitting power from the engine to the wheelassembly; a fuel system arranged toward the front of the frame forproviding fuel to the engine; and a saddle seat supported on the frameand located above the engine. The engine is oriented with its cylinderhead positioned toward the rear of the frame. A projection of thecylinder head on a vertical plane where side walls of the front and rearwheels on the same side of the vehicle are positioned is located at therear side of a projection of the midpoint of an imaginary lineconnecting centers of the front and rear wheels on the vertical plane,and the cylinder head is closer to the rear end of the frame.

Optionally, the fuel system includes a fuel tank located toward thefront end of the frame.

Optionally, a projection of the center point of the fuel tank on thevertical plane where side walls of the front and rear wheels arepositioned is located below a projection of the highest point of thecylinder head on the vertical plane.

Optionally, the intake assembly includes an air filter; an air intakepipe connected to the air filter for air to enter into the air filter,and an air outlet pipe matched with the air filter for the filtered airto enter into the cylinder head. The air filter is located above thefuel tank.

Optionally, the inlet of the air intake pipe faces toward the rear endof the frame.

Optionally, the exhaust assembly includes a tubular muffler mounted onthe frame, inside of which is a catalyst for promoting redox of exhaustgas. An exhaust pipe is located between the tubular muffler and thecylinder head, one end of which is connected to the cylinder head, andthe other end is connected to a middle portion of the tubular muffler.

Optionally, the tubular muffler defines a resonance cavity, an exhaustcavity, and an air intake cavity arranged between the resonance cavityand the exhaust cavity. The exhaust pipe is connected to the air intakecavity. Exhaust gas enters into the resonance cavity through the airintake cavity, and then flows into the exhaust cavity through aninternal pipeline.

Optionally, a plurality of resonance tubes are provided inside of theresonance cavity. The side wall of each resonance tube defines aplurality of resonance holes for exhaust gas to enter into the resonancecavity.

Optionally, a portion of the internal pipe located in the resonancecavity defines a plurality of air holes for exhaust gas to enter intothe pipe.

Optionally, the tubular muffler defines a partial pressure chamberadjacent to the resonance cavity. One end of the internal pipe ispositioned in the partial pressure chamber, and exhaust gas enters intothe internal pipe through a pipe port.

Optionally, the engine also includes a transmission arranged on one sideof the main body of the engine. The straddle vehicle further includes abattery, and the frame is provided with a battery mounting positionarranged on the side away from the transmission.

Optionally, the battery mounting position is a battery support platearranged at a front lower position of the frame.

Optionally, the battery support plate defines at least one hole for heatdissipation.

Optionally, the frame includes an engine mounting position forsupporting the engine, and the bottom of the main body is provided withan inclined shock absorber connected to the engine mounting position toform an inverted v-shaped support for the engine.

Optionally, the engine mounting position is a bottom plate arranged onthe lower portion of the frame, and the bottom plate has at least oneflat surface.

Optionally, a cross-section of the bottom plate is an inverted v-shapedstructure.

Optionally, the bottom plate defines a plurality of holes.

Optionally, the parking assembly includes: a parking mechanism forbraking the vehicle while parked, a handbrake cable connected to theparking mechanism, and a handle. One end of the handle is hinged to theframe, the handle being connected to the handbrake cable and arranged onone side of the frame.

The present application also discloses a straddle vehicle, including: awheel assembly including front and rear wheels arranged under the frame;an engine mounted on the frame for providing power to the vehicle, whichincludes a main body and a cylinder head connected to the main body andpositioned above the main body; an intake and exhaust system, includingan intake assembly for supplying air to the engine and an exhaustassembly for discharging exhaust gas generated by the engine; a brakesystem associated with the wheel assembly, including a parking assemblyand a brake assembly; a transmission system installed on the frame fortransmitting power from the engine to the wheel assembly; a fuel systemarranged at a front end of the frame for providing fuel to the engine;and a saddle seat supported on the frame and located above the engine.The engine is oriented with its cylinder head positioned toward the rearof the frame. A projection of the center of gravity of the vehicle on avertical plane where side walls of the front and rear wheels on the sameside of the vehicle are positioned is located further forward than aprojection of the center of gravity of the engine on the vertical plane.

Optionally, the fuel system includes a fuel tank located toward thefront end of the frame. A projection of a center of the fuel tank on avertical plane is located further forward than a projection of thecenter of gravity of the vehicle on the vertical plane.

Optionally, the projection of the center point of the fuel tank on avertical plane is located below a projection of the highest point of thecylinder head on the vertical plane.

Optionally, the intake assembly includes an air filter; an air intakepipe connected to the air filter for allowing air to enter into the airfilter, and an air outlet pipe matched with the air filter for thefiltered air to enter into the cylinder head. The air filter is locatedabove the fuel tank.

Optionally, the inlet of the air intake pipe faces toward the rear endof the frame.

Optionally, the exhaust assembly includes a tubular muffler mounted onthe frame, inside of which is a catalyst for promoting redox of exhaustgas. An exhaust pipe is located between the tubular muffler and thecylinder head, one end of which is connected to the cylinder head, andthe other end is connected to a middle portion of the tubular muffler.

Optionally, the tubular muffler defines a resonance cavity, an exhaustcavity, and an air intake cavity arranged between the resonance cavityand the exhaust cavity. The exhaust pipe is connected to the air intakecavity. Exhaust gas enters into the resonance cavity through the airintake cavity, and then flows into the exhaust cavity through aninternal pipe.

Optionally, a plurality of resonance tubes are provided inside of theresonance cavity. The side wall of each resonance tube defines aplurality of resonance holes for exhaust gas to enter into the resonancecavity.

Optionally, a portion of the internal pipe located in the resonancecavity defines a plurality of air holes for the exhaust gas to enterinto the pipe.

Optionally, the tubular muffler defines a partial pressure chamberadjacent to the resonance cavity. One end of the internal pipe ispositioned in the partial pressure chamber, and exhaust gas enters intothe pipe through a pipe port.

Optionally, the straddle vehicle further includes a battery.

The frame includes a battery mounting position arranged on the side awayfrom the transmission.

Optionally, the battery mounting position is a battery support platearranged at a front lower position of the frame.

Optionally, the battery support plate defines at least one hole for heatdissipation.

Optionally, the frame includes an engine mounting position forsupporting the engine, and the bottom of the main body is provided withan inclined shock absorber connected to the engine mounting position toform an inverted v-shaped support for the engine.

Optionally, the engine mounting position is a bottom plate arranged onthe lower portion of the frame, and the bottom plate has at least oneflat surface.

Optionally, a cross-section of the bottom plate is an inverted v-shapedstructure.

Optionally, the bottom plate defines a plurality of holes.

Optionally, the parking assembly includes: a parking mechanism forbraking the vehicle while parked, a handbrake cable connected to theparking mechanism and a handle. One end of the handle is hinged to theframe, the handle being connected to the handbrake cable and arranged onone side of the frame.

The present application also discloses a straddle vehicle, including: aframe; a wheel assembly including front and rear wheels arranged underthe frame; an engine mounted on the frame for providing power to thevehicle, the engine including a main body and a cylinder head connectedto the main body and positioned above the main body; an intake andexhaust system, including an intake assembly for supplying air to theengine and an exhaust assembly for discharging exhaust gas generated bythe engine; a brake system associated with the wheel assembly, includinga parking assembly and a brake assembly; a transmission system installedon the frame for transmitting power from the engine to the wheelassembly; a fuel system arranged toward the front of the frame forproviding fuel to the engine; and a saddle seat supported on the frameand located above the engine. A center line of the vehicle is definedalong the length direction of the vehicle. A projection of the cylinderhead on an imaginary plane including center lines of the two frontwheels and the two rear wheels of the vehicle is located above aprojection of the center line of vehicle on the imaginary plane.

Optionally, the fuel system includes a fuel tank, a fuel pipe used forconveying fuel from the fuel tank to the engine, and a fuel pump forpumping fuel from the fuel tank to the fuel pipe. The fuel tank islocated toward the front end of the frame.

Optionally, a projection of the center point of the fuel tank on avertical plane where side walls of the front and rear wheels arepositioned is located below a projection of the highest point of thecylinder head on the vertical plane.

Optionally, the intake assembly includes an air filter; an air intakepipe connected to the air filter for air to enter into the air filter,and an air outlet pipe matched with the air filter for the filtered airto enter into the cylinder head. The air filter is located above thefuel tank.

Optionally, the inlet of the air intake pipe faces toward the rear endof the frame.

Optionally, the exhaust assembly includes: a tubular muffler mounted onthe frame, inside of which is a catalyst for promoting redox of exhaustgas. An exhaust pipe is located between the tubular muffler and thecylinder head, one end of which is connected to the cylinder head, andthe other end is connected to a middle portion of the tubular muffler.

Optionally, the tubular muffler defines a resonance cavity, an exhaustcavity, and an air intake cavity arranged between the resonance cavityand the exhaust cavity. The exhaust pipe is connected to the air intakecavity. Exhaust gas enters into the resonance cavity through the airintake cavity, and then flows into the exhaust cavity through aninternal pipe.

Optionally, a plurality of resonance tubes are provided. A side wall ofeach resonance tube defines a plurality of resonance holes for exhaustgas to enter into the resonance cavity.

Optionally, a portion of the internal pipe located in the resonancecavity defines a plurality of air holes for exhaust gas to enter intothe pipe.

Optionally, the tubular muffler defines a partial pressure chamberadjacent to the resonance cavity. One end of the internal pipe ispositioned in the partial pressure chamber, and exhaust gas enters intothe internal pipe through a pipe port.

Optionally, the frame includes a battery mounting position arranged onthe side away from the transmission.

Optionally, the battery mounting position is a battery support platearranged at a front lower position of the frame.

Optionally, the battery support plate defines at least one hole for heatdissipation.

Optionally, the frame includes an engine mounting position forsupporting the engine, and the bottom of the main body is provided withan inclined shock absorber connected to the engine mounting position toform an inverted v-shaped support for the engine.

Optionally, the engine mounting position is a bottom plate arranged onthe lower portion of the frame, and the bottom plate has at least oneflat surface.

Optionally, a cross-section of the bottom plate is an inverted v-shapedstructure.

Optionally, the bottom plate defines a plurality of holes.

Optionally, the parking assembly includes: a parking mechanism forbraking the vehicle while parked, a handbrake cable connected to theparking mechanism, and a handle. One end of the handle is hinged to theframe, the handle being connected to the handbrake cable and arranged onone side of the frame.

The present application also discloses a straddle vehicle including anengine mounted on a frame, wherein, the side of the cylinder head of theengine is closer to the rear end of the frame than to the front end ofthe frame, and the connecting port on the cylinder head for connectingthe exhaust pipe faces toward the rear end of the frame.

Optionally, the exhaust pipe is provided with a tubular mufflerincluding an air inlet and an air outlet, with the air inlet beinglocated in the middle of a circumferential wall of the tubular muffler.

Optionally, the air outlet is arranged at a rear lower end of thecircumferential wall of the tubular muffler.

Optionally, the tubular muffler includes a tubular body. A middleportion of the tubular body defines an air intake chamber directlyconnected to the air inlet. The tubular body defines a front mufflingchamber at the front end of the air intake chamber and a rear mufflingchamber at the back end of the air intake chamber. The air intakechamber communicates with the front muffling chamber, the front mufflingchamber communicates with the rear muffling chamber through a connectingpipe, and the air outlet communicates with the rear muffling chamber.

Optionally, an inner portion of both the front muffling chamber and therear muffling chamber includes a porous structure for suction.

Optionally, a connecting position for fixing the engine is arranged onthe frame at a position corresponding to the bottom of the engine.

Optionally, the connecting position includes a front connecting positionarranged nearer to the front end of the frame and a rear connectingposition arranged nearer to the back end of the frame.

Optionally, a predetermined inclination angle is defined between aconnection plane of the front connection position and/or the rearconnection position and a bottom plane of the engine.

Optionally, the predetermined inclination angle is in the range from 15°to 45°.

Optionally, the straddle vehicle further includes: a wheel assembly,including front and rear wheels arranged under the frame; an intake andexhaust system, including an intake assembly for supplying air to theengine and an exhaust assembly for discharging exhaust gas generated bythe engine; a transmission system mounted on the frame for transmittingpower from the engine to the wheel assembly; and a fuel system arrangedtoward the front end of the frame for providing fuel to the engine.

Optionally, a projection of the cylinder head on a vertical plane whereside walls of the front and rear wheels on the same side of the vehicleare positioned is located at the rear side of a projection of a midpointof an imaginary line connecting centers of the front and rear wheels onthe vertical plane, and the cylinder head is closer to the rear end ofthe frame.

Optionally, the engine is oriented with its cylinder head positionedtoward the rear of the frame, and a projection of the center of gravityof the vehicle on a vertical plane where side walls of the front andrear wheels on the same side of the vehicle are positioned is locatedfurther forward than a projection of the center of gravity of the engineon the vertical plane.

Optionally, a center line of the vehicle is defined along the lengthdirection of the vehicle. A projection of the cylinder head on animaginary plane including center lines of the two front wheels and thetwo rear wheels of the vehicle is located above a projection of thecenter line of vehicle on the imaginary plane.

Optionally, the cylinder head is positioned toward the rear end of theframe. Defining a horizontal distance between the center of the cylinderhead and a front axle of the vehicle as L_(e), and defining a horizontaldistance between the center of the cylinder head and a rear axle of thevehicle as L_(f), L_(e)≥2L_(f).

Optionally, the connecting port on the cylinder head for connecting theexhaust pipe faces toward the tubular muffler.

The present application also discloses a straddle vehicle, including: aframe; a wheel assembly including front and rear wheels arranged underthe frame; an engine mounted on the frame for providing power to thevehicle, the engine including a main body and a cylinder head connectedto the main body and positioned above the main body; an intake andexhaust system, including an intake assembly for supplying air to theengine and an exhaust assembly for discharging exhaust gas generated bythe engine; a brake system associated with the wheel assembly, includinga parking assembly and a brake assembly; a transmission system mountedon the frame for transmitting power from the engine to the wheelassembly; a fuel system arranged toward the front of the frame forproviding fuel to the engine; and a saddle seat supported on the frameand located above the engine. The engine is oriented with its cylinderhead positioned toward the rear of the frame. Defining a horizontaldistance between a center of the cylinder head and a front axle of thevehicle as L_(e), and defining a horizontal distance between the centerof the cylinder head and a rear axle of the vehicle as L_(f),L_(e)≥2L_(f).

Optionally, the fuel system includes a fuel tank located toward thefront end of the frame.

Optionally, a projection of the center point of the fuel tank on thevertical plane where side walls of the front and rear wheels arepositioned is located below a projection of the highest point of thecylinder head on that plane.

Optionally, the intake assembly includes an air filter; an air intakepipe connected to the air filter for air to enter into the air filter,and an air outlet pipe matched with the air filter for the filtered airto enter into the cylinder head. The air filter is located above thefuel tank.

Optionally, the inlet of the air intake pipe faces toward the rear endof the frame.

Optionally, the exhaust assembly includes a tubular muffler mounted onthe frame, inside of which is a catalyst for promoting redox of exhaustgas. An exhaust pipe is located between the tubular muffler and thecylinder head, one end of which is connected to the cylinder head, andthe other end is connected to a middle portion of the tubular muffler.

Optionally, the tubular muffler defines a resonance cavity, an exhaustcavity, and an air intake cavity arranged between the resonance cavityand the exhaust cavity. The exhaust pipe is connected to the air intakecavity. Exhaust gas enters into the resonance cavity through the airintake cavity, and then flows into the exhaust cavity through aninternal pipe.

Optionally, a plurality of resonance tubes are provided inside of theresonance cavity. The side wall of each resonance tube defines aplurality of resonance holes for exhaust gas to enter into the resonancecavity.

Optionally, a portion of the internal pipe located in the resonancecavity defines a plurality of air holes for exhaust gas to enter intothe pipe.

Optionally, the tubular muffler defines a partial pressure chamberadjacent to the resonance cavity. One end of the internal pipe ispositioned in the partial pressure chamber, and exhaust gas enters intothe internal pipe through a pipe port.

Optionally, the engine also includes a transmission arranged on one sideof the main body. The straddle vehicle also includes a battery, and theframe is provided with a battery mounting position arranged on the sideaway from the transmission.

Optionally, the battery mounting position is a battery support platearranged at a front lower portion of the frame.

Optionally, the battery support plate defines at least one hole for heatdissipation.

Optionally, the frame includes an engine mounting position forsupporting the engine, and the bottom of the main body is provided withan inclined shock absorber connected to the engine mounting position toform an inverted v-shaped support for the engine.

Optionally, the engine mounting position is a bottom plate arranged on alower portion of the frame, and the bottom plate has at least one flatsurface.

Optionally, a cross-section of the bottom plate is an inverted v-shapedstructure.

Optionally, the bottom plate defines a plurality of holes.

Optionally, the parking assembly includes: a parking mechanism forbraking the vehicle while parked, a handbrake cable connected to theparking mechanism, and a handle. One end of the handle is hinged to theframe, the handle being connected to the handbrake cable and arranged onone side of the frame.

The present application also discloses a straddle vehicle, including: aframe; a wheel assembly including front and rear wheels arranged underthe frame; an engine mounted on the frame for providing power to thevehicle, which includes a main body and a cylinder head connected to themain body and positioned above the main body; the cylinder headincluding an exhaust port for discharging exhaust gas; an intake andexhaust system, including an intake assembly for supplying air to theengine and an exhaust assembly for discharging exhaust gas generated bythe engine; the exhaust assembly including an exhaust pipe connected tothe cylinder head and a tubular muffler connected to the exhaust pipe; abrake system associated with the wheel assembly, including a parkingassembly and a brake assembly; a transmission system mounted on theframe for transmitting power from the engine to the wheel assembly; afuel system arranged at the front end of the frame for providing fuel tothe engine; and a saddle seat supported on the frame and located abovethe engine. The engine is oriented with its cylinder head positionedtoward the rear of the frame, and the opening direction of the exhaustport faces toward the tubular muffler.

Optionally, the fuel system includes a fuel tank located toward a frontend of the frame.

Optionally, a projection of the center point of the fuel tank on thevertical plane where side walls of the front and rear wheels arepositioned is located below a projection of the highest point of thecylinder head on that plane.

Optionally, the intake assembly includes an air filter, an air intakepipe connected to the air filter for air to enter into the air filter,and an air outlet pipe matched with the air filter for the filtered airto enter into the cylinder head. The air filter is located above thefuel tank.

Optionally, the inlet of the air intake pipe faces toward the rear endof the frame.

Optionally, one end of an exhaust pipe is connected to the cylinderhead, and the other end is connected to a middle portion of the tubularmuffler.

Optionally, the tubular muffler defines a resonance cavity, an exhaustcavity, and an air intake cavity arranged between the resonance cavityand the exhaust cavity. The exhaust pipe is connected to the air intakecavity. Exhaust gas enters into the resonance cavity through the airintake cavity, and then flows into the exhaust cavity through aninternal pipe.

Optionally, a plurality of resonance tubes are provided inside of theresonance cavity. The side wall of each resonance tube defines aplurality of resonance holes for exhaust gas to enter into the resonancecavity.

Optionally, a portion of the internal pipe located in the resonancecavity defines a plurality of air holes for exhaust gas to enter intothe pipe.

Optionally, the tubular muffler defines a partial pressure chamberadjacent to the resonance cavity. One end of the internal pipe ispositioned in the partial pressure chamber, and exhaust gas enters intothe internal pipe through a pipe port.

Optionally, the engine also includes a transmission arranged on one sideof the main body of the engine. The straddle vehicle also includes abattery, and the frame is provided with a battery mounting positionarranged on the side away from the transmission.

Optionally, the battery mounting position is a battery support platearranged at a front lower portion of the frame.

Optionally, the battery support plate defines at least one hole for heatdissipation.

Optionally, the frame includes an engine mounting position forsupporting the engine, and a bottom of the main body is provided with aninclined shock absorber connected to the engine mounting position toform an inverted v-shaped support for the engine.

Optionally, the engine mounting position is a bottom plate arranged onthe lower portion of the frame, and the bottom plate has at least oneflat surface.

Optionally, a cross-section of the bottom plate is an inverted v-shapedstructure.

Optionally, the bottom plate defines a plurality of holes.

Optionally, the parking assembly includes: a parking mechanism forbraking the vehicle while parked, a handbrake cable connected to theparking mechanism, and a handle. One end of the handle is hinged to theframe, the handle being connected to the handbrake cable and arranged onone side of the frame.

The present application also discloses a straddle vehicle, including: aframe; an engine for providing power to the vehicle, including atransmission, a main body and a cylinder head connected to the main bodyand positioned above the main body, the cylinder head including acylinder and a cylinder cover; an intake and exhaust system including anintake assembly for providing air to the engine and an exhaust assemblyfor exhausting waste gas generated by the engine; the exhaust assemblyincluding an exhaust pipe and a tubular muffler arranged at the rear endof the frame; a brake system including a parking assembly and a brakeassembly; a transmission system mounted on the frame for transmittingengine power to the wheels; a fuel system arranged at the front end ofthe frame for providing fuel to the power system; and a saddle seatsystem supported on the frame and located above the engine. The openingdirection of the exhaust channel on the cylinder cover faces toward thetubular muffler.

Optionally, the fuel system includes: a fuel tank arranged at the frontend of the frame.

Optionally, a center point of the fuel tank is positioned below thecylinder cover.

Optionally, the intake assembly includes an air filter, an air intakepipe connected to the air filter for air to enter into the air filter,and an air outlet pipe matched with the air filter for the filtered airto enter into the cylinder head. The air filter is located above thefuel tank.

Optionally, the inlet of the air intake pipe faces toward the rear endof the frame.

Optionally, one end of the exhaust pipe is connected to the cylinderhead, and the other end is connected to a middle portion of the tubularmuffler.

Optionally, the tubular muffler defines a resonance cavity, an exhaustcavity, and an air intake cavity arranged between the resonance cavityand the exhaust cavity. The exhaust pipe is connected to the air intakecavity. Exhaust gas enters into the resonance cavity through the airintake cavity, and then flows into the exhaust cavity through aninternal pipe.

Optionally, a plurality of resonance tubes are provided inside of theresonance cavity. The side wall of each resonance tube defines aplurality of resonance holes for exhaust gas to enter into the resonancecavity.

Optionally, a portion of the internal pipe located in the resonancecavity defines a plurality of air holes for exhaust gas to enter intothe pipe.

Optionally, the tubular muffler defines a partial pressure chamberadjacent to the resonance cavity. One end of the internal pipe ispositioned in the partial pressure chamber, and exhaust gas enters intothe internal pipe through a pipe port.

Optionally, the frame is provided with a battery mounting positionarranged on the side away from the transmission.

Optionally, the battery mounting position is a battery support platearranged at a front lower position of the frame.

Optionally, the battery support plate defines at least one hole for heatdissipation.

Optionally, the frame is provided with an engine mounting position forsupporting the engine, and a bottom of the main body is provided with aninclined shock absorber connected to the engine mounting position toform an inverted v-shaped support for the engine. The engine mountingposition is a bottom plate arranged on a lower portion of the frame, andthe bottom plate has at least one flat surface. A cross-section of thebottom plate is an inverted v-shaped structure. The bottom plate definesa plurality of holes.

Optionally, the parking assembly includes: a parking mechanism forbraking the vehicle while parked, a handbrake cable connected to theparking mechanism, and a handle. One end of the handle is hinged to aframe, the handle being connected to the handbrake cable and arranged onone side of the frame.

In summary, compared to the background technical introduction, theengine arrangement structure of the above-mentioned straddle-typevehicle includes the engine mounted on the frame. In the enginearrangement structure, the cylinder head is arranged on the side of theengine closer to the rear end of the frame, and the connecting port onthe cylinder head for connecting to the exhaust pipe faces toward therear end of the frame. By arranging the cylinder head on one side of theengine nearer to the rear end of the frame, and arranging the connectionport on the cylinder head for connecting to the exhaust pipe to facetoward the rear end of the frame, the exhaust pipe and the tubularmuffler need not be run through the length of the vehicle, and theexhaust pipe does not pass through the riding position of the driverlocated in the middle of the frame, so the temperature of the ridingposition of the driver is significantly reduced, and driving comfort isimproved.

In addition, the present application also provides a straddle-typevehicle, which includes an engine arrangement structure as described inany of the above solutions. As the engine arrangement structure of theabove straddle-type vehicle has the above technical effects, thestraddle vehicle with the above engine arrangement structure should alsohave the corresponding technical effects, which will not be repeatedhere.

In the present application, the position of the cylinder head is closeto the rear wheel of the vehicle, which allows the heated cylinder headof the engine and the exhaust pipe connected to the cylinder head tofurther spaced from the position where the legs contact with the vehiclewhile the user is driving the vehicle, so the effect of heat emittedfrom the cylinder head on the rider's comfort is reduced.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a straddle-type vehicle in an embodimentof the application.

FIG. 2 is a right side view of the straddle-type vehicle in FIG. 1.

FIG. 3 is a right side view of the engine and exhaust assemblies of thestraddle-type vehicle in FIG. 1 on the frame.

FIG. 4 is a plan view of the cylinder head in FIG. 1 projected on aCartesian coordinate system x-y.

FIG. 5 is a right side view of the engine in FIG. 1 on the frame.

FIG. 6 is a plan view of the cylinder head in FIG. 1 projected on aCartesian coordinate system a-b.

FIG. 7 is a plan view of the horizontal distance between the cylinderhead and the front axle of vehicle and of the horizontal distancebetween the cylinder head and the rear axle of the vehicle in FIG. 1.

FIG. 8 is a top view of the engine in FIG. 1 on the frame.

FIG. 9 is a schematic diagram of the structure of the engine, fuelsystem and intake and exhaust system on the frame in FIG. 1.

FIG. 10 is a perspective view of the fuel system and air intakeassemblies on the frame in FIG. 9.

FIG. 11 is a structural schematic diagram of the fuel system and airintake assemblies if FIG. 9 from another angle on the frame.

FIG. 12 is a perspective view of the structure of the frame system inFIG. 5.

FIG. 13 is a schematic diagram of the structure of the bottom plate onthe frame system in FIG. 12.

FIG. 14 is a schematic view of the structure of the shock absorber inFIG. 5.

FIG. 15 is a perspective view of the engine, fuel system and intake andexhaust systems in FIG. 6.

FIG. 16 is a perspective view of the engine, fuel system, and intake andexhaust system in FIG. 6 from another angle.

FIG. 17 is a schematic diagram of the structure of the tubular mufflerin FIG. 21.

FIG. 18 is a partial cross-sectional view of the tubular muffler in FIG.21.

FIG. 19 is a schematic front view of an engine arrangement structure ofa straddle-type vehicle provided in an embodiment of the presentapplication.

FIG. 20 is a top schematic view of the engine arrangement structure of astraddle-type vehicle provided by an embodiment of the presentapplication.

FIG. 21 is a side schematic view of the tubular muffler provided by anembodiment of the present application.

FIG. 22 is a top schematic view of the tubular muffler provided by anembodiment of the present application.

FIG. 23 is a schematic diagram of the internal structure of a tubularmuffler provided by an embodiment of the present application.

DETAILED DESCRIPTION

In order to enable those skilled in the art to better understand thepresent invention, the technical solutions in the embodiments of thepresent application are clearly and completely described below inconjunction with the accompanying drawings of the embodiments of thepresent application, and the structure or the related technical termsused in the present application are further described below. Anytechnical terms in the following should be understood and interpreted inaccordance with their general usage within the field unless otherwisespecified.

Referring to FIGS. 1-2 and 11-14, a straddle-type vehicle 100 providedby an embodiment of the present application includes engine 10, a frame20, a wheel assembly 30, an intake and exhaust system 40, a brake system50, a transmission system 60, a fuel system 70, a saddle seat 80, and anelectrical system 90. The engine 10 is arranged on the frame 20 forproviding power to the whole vehicle. The frame 20 may be a metallicframe used for supporting the engine 10, the intake and exhaust system40, the brake system 50, the transmission system 60, the fuel system 70,the saddle seat 80, and a plastic housing, etc. The wheel assembly 30includes a front wheel 31 and a rear wheel 32 arranged below the frame20. The intake and exhaust system 40 is connected to the engine 10. Thebrake system 50 is associated with the wheel assembly 30 for brakecontrol. The transmission system 60 is mounted on the frame 20 and isable to transmit the power of engine 10 to the wheel assembly 30. Thefuel system 70 is arranged at the front end of the frame to provide fuelto the engine 10. The saddle seat 80 is supported on the frame 20 andpositioned above the engine 10.

Referring to FIGS. 1-4 and 11-14, in the present embodiment, the engine10 includes an engine main body 14 and a cylinder head 11 connected tothe main body 14 and located above the main body 14. The engine 10 ismounted on the frame 20 and located at a lower portion of the frame 20,thereby the center of gravity of the entire vehicle 100 is effectivelylowered. Specifically, an engine mounting position is provided on theframe 20. The engine mounting position is composed of two bottom plates201 with spacing which are arranged at the lower portion of the frame20. The bottom plate 201 may be an inverted V-shaped structure. Ofcourse, it may also have other shapes, for example, an inclined flatplate, or a metal tube with an inclined plane. Four shock absorbers 141are connected to the bottom of the engine body 14. The shock absorbers141 can absorb the vibration of the engine 20 to improve the stabilityof the vehicle 100 and reduce noise. Two shock absorbers 141 are mountedon one of the bottom plates 201 and the other two shock absorbers 141are mounted on the other bottom plate 201. The shock absorbers 141 areinclined with a predetermined angle in the range from 15° to 45°.Specifically, the shock absorber 141 includes an upper connecting plate1411, a lower connecting plate 1412 and a shock-absorbing damping block1413. The upper connecting plate 1411 is connected to a shaft at thebottom of the main body 14. The shock-absorbing damping block 1413 isarranged between the upper connecting plate 1411 and the lowerconnecting plate 1412. An upper end surface of the shock-absorbingdamping block 1413 is glued or otherwise connected to the upperconnecting plate 1411, and a bottom surface of the shock-absorbingdamping block 1413 is glued or otherwise connected to the lowerconnecting plate 1412. There is no direct connection between the lowerconnecting plate 1412 and the upper connecting plate 1411. The lowerconnecting plate 1412 may be connected to a base plate 201 by bolts.

The engine 10 further includes a transmission 13 located on one side ofthe engine main body 11. In the present embodiment, the transmission 13is a CVT transmission. It is understood that other types oftransmissions can alternatively be used. After the engine 10 is mountedon the frame 20, the engine cylinder is non-vertically slanted with thecylinder head 11 facing toward the rear end of the frame 20. Thecylinder head 11 is located below the saddle seat 80, which keeps thecylinder head 11 away from the rider's legs, and the heat emitted fromthe cylinder head 11 is insulated by the saddle seat 80. Therefore, theheat emitted from the cylinder head 11 is not transferred to the rider,which ensures the rider's comfort and also enhances the rider's safetywhile driving the vehicle 100.

As shown in FIGS. 1-4, the wheel assembly 30 includes a front wheel 31adjacent to the front end of the frame 20 and a rear wheel 32 adjacentto the rear end of the frame. The front wheel 31 is connected to thetransmission system 60 through the front axle 311, and the rear wheel 32is connected to the transmission system 60 through the rear axle 321. ACartesian coordinate system x-y is established parallel to a plane whereside walls of the front wheel 31 and rear wheel 32 are positioned. Boththe center of the front wheel 31 and the center of the rear wheel 32 arepoints on the axis x, and the midpoint of an imaginary line connectingthe centers of the front wheel 31 and the rear wheel 32 defines theorigin O of Cartesian coordinate system x-y. The projection of cylinderhead 11 onto the plane of the Cartesian coordinate system is located inthe first quadrant of the Cartesian coordinate system x-y; that is, thecylinder head 11 is located rearwardly from the midpoint of theimaginary line connecting the centers of the front wheel 31 and the rearwheel 32, and is therefore closer to the rear end of the frame 20 thanto the front end of the frame 20.

As shown in FIGS. 9-10, the fuel system 70 includes a fuel tank 701mounted on the frame 20. The fuel tank 701 is a thin-walled tank withits fuel tank position mounted by two spaced crossbars 202 on the frame20. The width between the two crossbars 221 is suitable for supportingthe fuel tank 701. The fuel tank 701 is positioned on the two crossbars221 and supported by the crossbars 221 to fix the position of the fueltank 701 on the frame 20 so the fuel tank 701 has high stability. Theprojection of the fuel tank 701 onto the plane of the Cartesiancoordinate system x-y is located in the second quadrant of the Cartesiancoordinate system x-y. As such, the fuel tank 701 is away from thecylinder head 11 and away from the heat source of the engine 10,resulting in less heating of the fuel tank 701 and increased safety ofthe fuel tank when mounted on the frame 20. The positioning keeps thefuel temperature in the fuel tank 701 low, resulting in less fuelvolatilization. The projection of the center point of the fuel tank 701on the plane of the Cartesian coordinate system is located below theprojection of the highest point of the cylinder head 11 on the plane ofthe Cartesian coordinate system, nearer to the front end of the frame.The positioning results in a lower mounting height of the fuel tank 701on the frame 20, thereby reducing the center of gravity of the wholevehicle, so the vehicle has high stability during turning of thevehicle.

As shown in FIGS. 9-11, the intake and exhaust system 40 includes anintake assembly 41 and an exhaust assembly 42. The intake assembly 41 isused to provide clean air to the engine 10 to maintain efficientcombustion of fuel in the combustion chamber of the engine 10. Theintake assembly 41 includes an air filter 411, an air intake pipe 412and an air outlet pipe 413, wherein the air intake pipe 412 is connectedto the air filter 411 to allow air to enter into the air filter 41 tofilter out impurities in the air. The air outlet pipe 413 is connectedto the engine 10, and the filtered air is transmitted to the engine 10through the air outlet pipe 413, so as to provide oxygen for the fuel.In particular, the air filter 411 is located above the fuel tank 701 andfixed on the frame 20 by bolts. This positioning increases the mountingheight of the air filter 411 on the vehicle, resulting in cleaner airentering into the air filter 411 and a longer service life of the airfilter 411. At the same time, the air intake pipe 412 is arranged at thefront end of the air filter 411, and the air intake pipe 412 is curvedsuch that the inlet 412 a of the air intake pipe 412 faces rearwardly.Orienting the inlet 412 a rearwardly helps to prevent solid particles inthe air from being passively poured into the air filter 411 duringvehicle driving, and ensures that the air intake of the air filter 411is reasonable.

As shown in FIGS. 15-18, the exhaust assembly 42 includes a tubularmuffler 421 and an exhaust pipe 422 connected to the tubular muffler 421and cylinder head 11. The tubular muffler 421 is arranged at the rearend of the frame 20. A connecting block 424 is provided on the tubularmuffler 421. The connecting block 424 is a metal block closely attachedto the outer wall of the tubular muffler 421 which indirectly connectsthe tubular muffler 421 to the frame 20. The tubular muffler 421 definesa resonance cavity 4212, an exhaust cavity 4213, an air intake cavity4214 and a partial pressure chamber 4215. Exhaust gas enters the airintake cavity 4214 through the exhaust pipe 422, and then flows from theair intake cavity 4214 into the resonance cavity 4212. Exhaust gas isinternally piped both from the resonance cavity 4212 and from thepartial pressure chamber 4215 into the exhaust cavity 4213. The airintake cavity 4214 may be located in a middle portion of the tubularmuffler 421. The volume of the air intake cavity 4214 is larger than anyof the volumes of the resonance cavity 4212, the exhaust cavity 4213 orthe partial pressure chamber 4215. A catalyst is provided within the airintake cavity 4214 for promoting exhaust gas redox. The exhaust pipe 422is connected to the middle portion of the tubular muffler 421, that is,the exhaust pipe 422 is connected to the air intake cavity 4214. Thispositioning extends the length of the exhaust pipe 422, reduces thecurvature of the exhaust pipe 422, and reduces the resistance of theexhaust flow. Further, the partial pressure chamber 4215 is located atthe front of the tubular muffler 421, and the resonance cavity 4212 islocated between the air intake cavity 4214 and the partial pressurechamber 4215. The exhaust cavity 4213 is located at the rear of thetubular muffler 421, with the exhaust cavity 4213 being adjacent to theair intake cavity 4214.

In particular, a plurality of resonance tubes 4216 with openings at bothends are arranged in the resonance cavity 4212, and the resonance tubes4216 communicate with the air intake cavity 4214 and the partialpressure chamber 4215. A plurality of resonance holes 4217 are definedon the side wall of the resonance tube 4216. The exhaust gas in the airintake cavity 4214 flows in through one end of the resonance tube 4216,and then one portion of the exhaust gas flows into the resonance cavity4212 through the resonance holes 4217, and the other portion of theexhaust gas flows into the partial pressure chamber 4215 through theother end of the resonance tube 4216. A pipe 4218 within the tubularmuffler 421 connects the resonance cavity 4212 and the exhaust cavity4213 and also connects the partial pressure chamber 4215 and the exhaustcavity 4213. The pipe 4218 has openings on both ends, and a plurality ofair holes are arranged on the side wall of the portion of the pipe 4218located in the resonance cavity 4212. The exhaust gas in the resonancecavity 4212 enters the pipe 4218 through the air holes, and then flowsinto the exhaust cavity 4213. One end of the pipe 4218 is positioned inthe partial pressure chamber 4215. The exhaust gas in the partialpressure chamber 4215 flows into the pipe 4218 through one end of thepipe 4218, and flows into the exhaust cavity 4213 through the pipe 4218.

Further, the tubular muffler 421 is provided with a tail gas pipe 423which is connected to the exhaust cavity 4213, and the exhaust gasentering the exhaust cavity 4213 is discharged into the outside airthrough the tail gas pipe 423. The position of the tail gas pipe 423 ispreferably at a lower end of the circumferential wall of the tubularmuffler 421. Specifically, the tail gas pipe 423 is curved, and theoutlet for exhaust gas of the tail gas pipe 423 is inclined and alignedwith the bottom plane of the lower end. One end where the tail gas pipe423 is connected to the exhaust cavity 4213 is inserted into the exhaustcavity 4213 extends vertically within the exhaust cavity 4213.

As shown in FIGS. 11-12, the electrical system 90 includes a battery 91for providing power for ignition of the engine 10 as well as otherelectrical elements of the vehicle. The battery 91 is located at thefront lower portion of the frame 20 and is close to the engine 10. Thebattery 91 is located on the side away from the transmission 13, so thatthe heat of the transmission 13 is not transmitted to the battery 91,which lowers the working temperature of the battery 91, increases theworking life of the battery 91, and eliminates the potential safetyhazard of the battery 91 exploding due to overheating. In particular, abattery mounting position is provided on the frame 20, which includes abattery support plate 203 fixed on the frame 20. The battery supportplate 203 is located at the lower portion of the frame 20 and on theside away from the transmission 13. The battery 91 is placed on thebattery support plate 203. The edges of the battery support plate 203are upturned to form a flange 2031 such that battery movement is limitedby the flange 2031. The flange 2031 enables heat dissipation from thebattery 91 and ensures the battery 91 is stable and is not easily moved.The center of the battery support plate 203 can additionally define aheat dissipation hole 2032 to increase the heat dissipation of thebattery 91 and keep the battery 91 working at normal temperature.

As shown in FIGS. 1-2, the brake system 50 includes a parking assemblyor assembly 51 to prevent the vehicle 100 from moving after the vehicle100 has been parked. The parking assembly 51 includes a parkingmechanism 511, a handbrake cable 512 and a handle 513. One end of thehandbrake cable 512 is connected to the parking mechanism 511, and theother end is connected to the handle 513. By pulling the handle 513, theforce on the handle 513 is transmitted to the parking mechanism 511through the handbrake cable 512, thereby engaging a parking brake forthe vehicle 100. In particular, one end of the handle 513 is indirectlyand rotatably connected to one side of the frame 20. When using thehandle 513, only one end of the handle 513 needs to be pulled so thatthe handle can be rotated to a certain angle. The handle 513 is arrangedon one side of the fuel tank 701 of the vehicle 100 and is close to thefront end of the saddle seat 80, a position which is convenient and easyfor pulling the handle 513, saving time and effort. A shift lever 601 isindirectly arranged on the frame 20 and close to the front end of thesaddle seat 80. The position of the shift lever 601 corresponds to theposition of the handle 513, that is, the shift lever 601 is arranged onone side of the frame, and the handle 513 is arranged on the other sideof the frame, which is convenient for manual gear shifting when drivingthe vehicle.

As shown in FIGS. 1-3 and 5, point A is the center of gravity of thevehicle 100, and point B is the center of gravity of the engine 10. Theprojection of point A on the plane of the Cartesian coordinate systemx-y is located on the front side of the projection of point B on theplane of the Cartesian coordinate system x-y, that is, the horizontaldistance between point B and the axle center of the rear wheels 32 isless than the horizontal distance between point A and the axle center ofthe rear wheels 32. FIGS. show only portions of the preferredembodiment, which are understood to include structures identical orsimilar to those of other Figures, the description of which is notrepeated here.

As shown in FIGS. 1-3 and 6, a distance between a center of the cylinderhead 11 of the engine and the front axle 311 is L_(e), and a distancebetween a center of the cylinder head 11 and the rear axle 321 is L_(f),wherein, L_(e)≥L_(f). FIGS. show only portions of the preferredembodiment, which are understood to include structures identical orsimilar to those of other Figures, the description of which is notrepeated here.

As shown in FIGS. 1-3 and 7, the Cartesian coordinate system a-b isestablished on a plane of imaginary lines connecting the centers of thetwo front wheels 31 and the centers of the two rear wheels 32 of thevehicle 100, wherein, axis a is the horizontal axis of the Cartesiancoordinate system a-b, axis b is the vertical axis as drawn, and theorigin is the intersection point. The projection of the wheelbasecenterline along the length direction of the vehicle 100 on the plane ofthe Cartesian coordinate system coincides with axis a, and theprojection of the vehicle centerline along the width direction of thevehicle on the plane of the Cartesian coordinate system a-b coincideswith the axis b. The projection of the midpoint c of the cylinder head11 on the plane of the Cartesian coordinate system a-b is located in thefirst quadrant of the Cartesian coordinate system a-b above thewheelbase centerline. FIGS. show only portions of the preferredembodiment, which are understood to include structures identical orsimilar to those of other Figures, the description of which is notrepeated here.

As shown in FIGS. 1-3 and 8, the opening direction of the exhaust porton the cylinder head 11 faces toward the tubular muffler 421. FIGS. showonly portions of the preferred embodiment, which are understood toinclude structures identical or similar to those of other Figures, thedescription of which is not repeated here.

As shown in FIGS. 1-5 and 19-23, the present embodiment of the inventionprovides an engine arrangement structure for a straddle-type vehicle,including a frame 25 and an engine 15 fixed on the frame 25. Thecylinder is slanted with the cylinder head 151 of the engine 15 ispositioned toward the rear of the frame 25. The connection port forconnecting the exhaust pipe 152 to the cylinder head 151 faces towardthe rear of the frame 25.

By arranging the cylinder head 151 of the engine 15 toward the rear ofthe frame, and arranging the connection port of the cylinder head 151 tothe exhaust pipe 152 facing toward the rear of the frame 25, the exhaustpipe 152 and the tubular muffler 35 need not run the whole length of thevehicle. The exhaust pipe does not pass through the riding position ofthe driver located in the middle of the frame 25, so the temperature ofthe riding position of the driver is significantly reduced, and drivingcomfort is improved.

It should be noted here that for those skilled in this art,straddle-type vehicles are generally provided with single-cylinderengines, and the cylinder head 151 of the single-cylinder engine isconnected to an exhaust pipe 152 through which exhaust gas isdischarged.

In more preferred embodiments, the cylinder head 151 of the engine 15 ispositioned toward the rear end of the frame 25, and the connection portof the cylinder head 151 which connects to the exhaust pipe 152 is alsofacing rearwardly. These orientations reduce the space available for themuffler. In order to meet the space requirements for the muffler, themuffler is preferably a tubular muffler 35 including an air inlet 36 andan air outlet 37, with the air inlet 36 of the tubular muffler 35arranged in the middle portion of the circumferential wall of thetubular muffler 35. Thereby, the arrangement space of the muffler can beeffectively saved.

In more preferred embodiments, the air outlet 37 of the tubular muffler35 is arranged at a rear lower end of the circumferential wall of thetubular muffler 35. This arrangement can prevent precipitation fromentering the inside of the tubular muffler 35, extending the normalservice life of the tubular muffler. Of course, it should be noted thatthe method of arranging the air outlet 37 at the rear lower end of thecircumferential wall of the tubular muffler 35 is only a most preferredembodiment of the present invention. In other embodiments, the airoutlet 37 may also be arranged at the rear end face of the tubularmuffler 35, or may be arranged at another position according to demandrequirements.

It should be noted here that, as shown in FIG. 5, the above-discussedtubular muffler 35 includes a tubular body 351, the middle portion ofwhich is provided with an air intake chamber 3511 which is directlyconnected to the air inlet 36. The tubular muffler 35 includes a frontmuffling chamber 3512 at the front end of the air intake chamber 3511and a rear muffling chamber 3513 at the back end of the air intakechamber 3511. The air intake chamber 3511 communicates with the frontmuffling chamber 3512, the front muffling chamber 3512 communicates withthe rear muffling chamber 3513 through a connecting pipe 3514, and theair outlet 37 communicates with the rear muffling chamber 3513. Throughthis structure of the tubular muffler 35, the exhaust gas path is thatthe exhaust gas enters into the air intake chamber 3511 from the airinlet port 36, and then flows into the front muffler chamber 3512 forpreliminary muffling, and then the exhaust gas in the front mufflingchamber 3512 is introduced into the rear muffling chamber 3513 throughthe connecting pipe 3514 for muffling again, and finally the exhaust gasis discharged through the air outlet 37 connected to the rear mufflingchamber 3513. By adopting this structure of the tubular muffler 35, thearrangement space of the muffler can be reduced. The double mufflingstructure also better enhances the silencing effect of the muffler. Itshould also be noted that the top of the tubular body of the tubularmuffler 35 is generally provided with a mounting position 38 forconvenient installation on the vehicle body. The specific structure ofthe mounting position 38 can adopt a double lifting lug structure, orthe other structures commonly used by those skilled in this art and notspecified here. A double-layered sandwich structure of sound-absorbingmaterials is generally arranged on the wall of the tubular body toensure good silencing effect of the muffler. The structure of the wallof the tubular body may include a double-layer stainless steel plate,the middle of which is filled with sound-absorbing cotton and othersound-absorbing materials. In addition, it should be noted that theinner portions of both the front muffling chamber 3512 and the rearmuffling chamber 3513 are generally provided with a porous structure forsound absorption 350, which belongs to the prior art known to thoseskilled in this field and is not further described in detail here.

In some more specific embodiments, a connection position 251 for fixingthe engine 15 is arranged on the frame 25 at a position corresponding tothe bottom of the engine 15. Of course, it should be understood thatlocating the connecting position at the bottom of the engine is only apreferred embodiment of the present invention, and the connectingposition can be located elsewhere according to demand requirements.

In a preferred embodiment, the connection position 251 includes a frontconnection position 2511 arranged nearer to the front end of the frame25 and a rear connection position 2512 arranged nearer to the rear endof the frame 25. In order to improve the stability of the engine 15fixed on the frame 25 and avoided the lateral movement of the engine 15relative to the frame 25, a predetermined inclination angle is definedbetween the connection plane of the front connection position 2511and/or the rear connection position 2512 and the bottom plane of engine15. By setting a predetermined inclination angle, the connecting planeof connection position 251 can support and fix the engine 15 through aninclined plane while laterally limiting the engine 15 relative to theengine frame 25 at the same time, which makes the fixation more stableand reliable.

In a further technical solution, the predetermined inclination angle isgenerally preferred to be in the range from 15° to 45°. Of course, itcan be understood that this is only the preferred example of thespecific numerical value for the predetermined inclination angle, and analternative predetermined angle value can be selected according todemand requirements.

In addition, the present invention also provides a straddle-type vehiclewhich includes the engine arrangement structure as described in any ofthe embodiments. As the engine arrangement structure of the abovestraddle-type vehicle results in the above described technical benefits,a straddle-type vehicle with such an engine arrangement structure alsoresults in the corresponding technical benefits, which will not berepeated here.

The straddle-type vehicle and the arrangement structure of the engineprovided by the present invention are described in detail above. Itshould be noted that each embodiment of the present specification isdescribed in a progressive manner, and each description focuses ondifferences from the other embodiments. Similar aspects between thevarious embodiments can be implied by reference to descriptions of otherembodiments.

It should also be noted that, in this description, terms such as“including”, “containing” or any other variations are intended to be anon-exclusive inclusion, so that items or equipment including a seriesof elements include not only those elements but also other elements thatare not explicitly listed but are inherent to such items or equipment.In the absence of more restrictions, the element modified by thestatement “including a” does not exclude such non-listed items orequipment.

All patents and publications referred to in this applicationspecification are publicly available technologies in the field, whichmay be used to modify the preferred embodiments in this application. Allthe patents and publications cited in the references could also be usedto modify the preferred structures individually referred to herein. Thepresent application can be implemented in the absence of any one or moreelements or one or more restrictions which are not specified in theindependent claims. The terms and expressions used herein are fordescription of the most preferred embodiments only, and the invention isnot limited by such descriptions of any preferred embodiments, nor isthere any intention to indicate that the terms and interpretationsdescribed in this application specification exclude any equivalentfeatures. Instead, workers skilled in the art know that any appropriateimprovements or modifications may be made within the scope of thisapplication and claims. Understandably, the embodiments described in thepresent application are some preferred embodiments and features, and anygeneral technical personnel in this art can make some improvements andmodifications in accordance with the spirit described in thisapplication. Such improvements and modifications are also deemed to fallinto the scopes both of this application and of the limitations of theindependent and dependent claims.

1-18. (canceled)
 19. A straddle-type vehicle comprising: a framedefining a front end and a rear end; a wheel assembly including frontand rear wheels arranged under the frame; an engine mounted on the framefor providing power to the vehicle, which comprises a main body and acylinder head connected to the main body and positioned above the mainbody; an intake and exhaust system, comprising an intake assembly forsupplying air to the engine and an exhaust assembly for dischargingexhaust gas generated by the engine; a brake system associated with thewheel assembly, comprising a parking component and a brake component; atransmission system installed on the frame for transmitting power fromthe engine to the wheel assembly; a fuel system arranged at a front endof the frame for providing fuel to the engine; and a saddle seatsupported on the frame and located above the engine; wherein, the engineis oriented with its cylinder head positioned toward the rear of theframe; and wherein a projection of the center of gravity of the vehicleon a vertical plane where side walls of the front and rear wheels on thesame side of the vehicle are positioned is located further forward thana projection of the center of gravity of the engine on the verticalplane.
 20. The straddle-type vehicle of claim 19, wherein the fuelsystem comprises: a fuel tank located toward the front end of the frame;and a projection of a center point of the fuel tank on the verticalplane is located further forward than a projection of the center ofgravity of the vehicle on the vertical plane.
 21. The straddle-typevehicle of claim 20 wherein the projection of the center point of thefuel tank on the vertical plane is located below a projection of thehighest point of the cylinder head on the vertical plane.
 22. Thestraddle-type vehicle of claim 20, wherein the intake assemblycomprises: an air filter; an air intake pipe connected to the air filterfor allowing air to enter into the air filter; and an air outlet pipematched with the air filter for filtered air to enter into the cylinderhead; wherein the air filter is located above the fuel tank.
 23. Thestraddle-type vehicle of claim 22, wherein an inlet of the air intakepipe faces toward the rear end of the frame.
 24. The straddle-typevehicle of claim 20, wherein the exhaust assembly comprises: a tubularmuffler mounted on the frame, inside of which is a catalyst forpromoting redox of exhaust gas; and an exhaust pipe located between thetubular muffler and the cylinder head, one end of which is connected tothe cylinder head, and the other end is connected to a middle part ofthe tubular muffler.
 25. The straddle-type vehicle of claim 24, whereinthe tubular muffler defines: a resonance cavity; exhaust cavity; and anair intake cavity arranged between the resonance cavity and the exhaustcavity; wherein the exhaust pipe is connected to the air intake cavitysuch that exhaust gas enters into the resonance cavity through the airintake cavity, and then flows into the exhaust cavity through aninternal pipe.
 26. The straddle-type vehicle of claim 25, wherein aplurality of resonance tubes are provided inside of the resonancecavity, a side wall of each resonance tube defining a plurality ofresonance holes for exhaust gas to enter into the resonance cavity. 27.The straddle-type vehicle of claim 25, wherein a portion of the internalpipe located in the resonant cavity defines a plurality of air holes forthe exhaust gas to enter into the internal pipe.
 28. The straddle-typevehicle of claim 27, wherein the tubular muffler defines a partialpressure chamber adjacent to the resonance cavity, one end of theinternal pipe being positioned in the partial pressure chamber, withexhaust gas entering into the internal pipe through a pipe port.
 29. Thestraddle-type vehicle of claim 19, wherein the straddle-type vehiclefurther comprises: a battery; and wherein the frame includes a batterymounting position arranged on the side away from the transmission. 30.The straddle-type vehicle of claim 29, wherein the battery mountingposition is a battery support plate arranged at a front lower part ofthe frame.
 31. The straddle-type vehicle of claim 30, wherein thebattery support plate defines at least one hole for heat dissipation.32. The straddle-type vehicle of claim 19, wherein the frame comprisesan engine mounting position for supporting the engine; and wherein abottom of the main body is provided with an inclined shock absorberconnected to the engine mounting position to form an inverted v-shapedsupport for the engine.
 33. The straddle-type vehicle of claim 32,wherein the engine mounting position is a bottom plate arranged on alower portion of the frame, and the bottom plate has at least one flatsurface.
 34. The straddle-type vehicle of claim 33, wherein a crosssection of the bottom plate is an inverted v-shaped structure.
 35. Thestraddle-type vehicle of claim 34, wherein the bottom plate defines aplurality of holes.
 36. The straddle-type vehicle of claim 19, whereinthe parking component comprises: a parking mechanism for braking thevehicle while parked; a handbrake cable connected to the parkingmechanism; and a handle, one end of which is hinged to the frame, thehandle being connected to the handbrake cable and arranged on one sideof the frame. 37-54. (canceled)
 55. A straddle-type vehicle comprisingan engine with a cylinder head mounted on a frame, the frame defining afront end and a rear end, wherein the engine is oriented with itscylinder closer to the rear end of the frame, and a connecting port onthe cylinder head for connecting an exhaust pipe faces toward the rearend of the frame.
 56. The straddle-type vehicle of claim 55, wherein theexhaust pipe is provided with a tubular muffler comprising an air inletand an air outlet, and wherein the air inlet is arranged in a middle ofa circumferential wail of the tubular muffler.
 57. The straddle-typevehicle of claim 56, wherein the air outlet is arranged at a rear lowerend of the circumferential wall of the tubular muffler.
 58. Thestraddle-type vehicle of claim 57, wherein the tubular muffler includesa tubular body, a middle portion of the tubular body defines an airintake chamber directly connected to the air inlet, the tubular bodydefines a front muffling chamber at a front end of the air intakechamber and a rear muffling chamber at a back end of the air intakechamber; the air intake chamber is connected to the front mufflingchamber, the front muffling chamber is connected to the rear mufflingchamber through an internal connecting pipe, and the air outlet isconnected to the rear muffling chamber.
 59. The straddle-type vehicle ofclaim 58, wherein an inner portion of both the front muffling chamberand the rear muffling chamber includes a porous structure for soundabsorption.
 60. The straddle-type vehicle of claim 55, wherein aconnecting position for fixing the engine is arranged on the framecorresponding to a bottom position of the engine.
 61. The straddle-typevehicle of claim 60, wherein the connecting position includes a frontconnecting position arranged adjacent to the front end of the frame anda rear connecting position arranged adjacent to the rear end of theframe.
 62. The straddle-type vehicle of claim 61, wherein apredetermined inclination angle is defined between a connection plane ofthe front connection position (9) and/or the rear connection position(10) and a bottom plane of the engine (2).
 63. The straddle-type vehicleof claim 62, wherein the predetermined. inclination angle is in a rangefrom 15° to 45°. 64-101. (canceled)